PROJECT SUMMARY Previous research has identified multiple biological, genetic, and behavioral factors that are associated with cognitive impairment and decline. Recently, a parallel literature has looked beyond individual-level factors to consider the role of the social and built environment. Findings suggest that residence in socioeconomically advantaged neighborhoods may promote cognitive function and/or buffer cognitive decline in part through their greater density of physical resources (recreational centers, gyms, parks, walking paths, healthy food stores) as well as social and institutional resources (libraries, bookstores, community centers, social clubs) that promote physical activity and facilitate mental stimulation (e.g. social interaction) that may buffer cognitive decline with age. However, these relationships have not been empirically tested with national population-based data. This study will examine the moderating role of neighborhood built and social environments on trajectories of cognitive function in a national, racially-diverse sample of Americans followed since 2003. We will identify how features of the social and built environment are related to rates of decline in cognitive function among participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. REGARDS is a national longitudinal cohort study of over 30,0000 black and white individuals age 45+ ongoing since 2003. In addition to being a longitudinal study collecting prospective data on cognitive function at annual intervals, the study also tracks residential locations through geographic coordinates that will be linked to secondary sources to characterize the surrounding social and built environment. The aims of this 4-year project are to i) characterize the built and social environment for respondents in the REGARDS study with respect to the physical and social resources that could mitigate cognitive decline; ii) use longitudinal data to examine the relationship between neighborhood resources and rates of cognitive decline over time; and iii) determine the extent to which built and social environments explain racial disparities in cognitive function. By augmenting this existing NIH-funded longitudinal cohort study with neighborhood characteristics, this study will provide a critical opportunity to examine the role of neighborhood built and social environments for preventing cognitive decline in Americans as they age.